Hydraulic pump



April 1950 E. EYNARD 2,503,614

HYDRAULIC PUMP Filed Dec. 29, 1945 3 Sheets-Sheet 1 IN V EN TOR.

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April 11, 1950 E. EYNARD 2,503,614

HYDRAULIC- PUMP Filed Dec. 29, 1945 3 Sheets-Sheet 3 am Apr. 11.1950 2 503 614 UNITED STATES 4 PATEN'E OFFIC mmfr... Applicatlonlllnecpsglzeer No. $37,935

Section 1, Public Law 890, August 8, 1948 Patent expi es March 25, 1964 9 Claims.

My invention refers to hydraulic pumps such as those intended to be used in connection with hydraulic rams or presses and like apparatus requiring a widely variable pressure increasing up to very high values.

In pumps of this kind it the pistons are so dimensioned as to provide easily high pressures, the output is necessarily reduced and the approach of the piston of the press is extremely slow. If on the contrary the pump is arranged to provide a rapid movement of the press, the maximum pressure remains limited on the one hand because the torquebecomes rapidly too high for a motor of average power. and on the other hand because the mechanical strength of the pump parts becomes insufficient.

A first object of my invention is to provide a pump which will permit of obtaining automatically an output and a pressure varying inversely of each other within extremely wide limits.

Another object or my invention is to provide a pump which will automatically require a substantially constant driving *torque irrespective of output and pressure variations.

-A further object of my invention is a pump of the aforesaid character, comprising a plurality of sets of pistons and cylinders of diflerent crossing I (Figs. 1 and 2) traversed by a fixed shalt 2 rotatably supporting a rotor 3 in which there are formed two rows oi radial cylinders, viz. respectively cylinders 4 of large diameter (Figs. 1 and 2) and cylinders 5 of smaller diameter (Figs. 1 and 3). Pistons 8 and I are slidable in cylinders 4 and 5 respectively and they are pivotally connected with shoes 8 and 8 adapted to slide in circular grooves l0 and II formed on the internal periphery of a drum member 12 enclosing rotor 3.

Drum I2 is not co-axial to shaft 2. It is retatably supported by bearings carried by side members l4 adapted to slide vertically against a slide 15 within casing I (Fig. 2). The two side members I4 are moreover connected by longitudl nal stays l6 (Figs. 1 and 2) fixed to vertical columns I! which pass through the upper part of casing I to carry a common connecting crossmember l8. I'he latter slides on vertical guide rods l9 provided-with strong compression springs 26 tending to push member l8 downwardly.

It will be understood that the above-described arrangement permits drum I2 to be displaced uptially zero eccentricity.

sections, and pressure-actuated means adapted to eliminate the sets of .larger cross-section as the pressure rises. This elimination is preferably effected by means of a by-pass while a non-return valve is provided to prevent liquid from flowing back from the high-pressure side of the pump.

Still a further object of my invention is a'pump or the aforesaid character, wherein the cylinders are radially disposed on the same rotating memher, the pistons being connected to a second rotating member eccentrically disposed with respect to the former. and means being provided to reduce this, eccentricitywhen the delivery pressure rises.

My improved pump also comprises a casing forming a tank for the liquid to be pumped and comprising a distributor to control the hydraulic press associated with the pump.

In the annexed drawings:

Fig. 1 is a general longitudinal section of a pump established in accordance with my invention.

Fig. 21s a transverse section thereof taken along line II-JI of Fig. 1. In thisFlg. 2 the plane of section of Fit. 1 is indicated by llne'I-.-'-I.

I Fig. 3 is a partial transverse section taken alon line 111-411 of Fig. 1.

1'18. 4 is another partial transverse takenalonglineIVIVofI"lg.1.

Fig. 5 is a fragmental section taken along line V-V of Fla. 2.

Cross-member I8 is also submitted to the action of a hydraulic device comprising a piston 2! (Figs. 1 and 2) slidable within a small vertical cylinder 22 provided above casing l. the said piston tending to push the said member upwardly. Piston 2| is made in twoparts with a mass or packing material between them. The upper part abuts against member 18 while the lower part is fixed on a rod which passes through the upper part and through member 18, and carries a compression spring 24 tending to push rod 23 upwardly to ensure perfect tightness of the packing.

Shaft 2 is formed as a distributor for the two sets of cylinders-4 and 5. It comprises a first hollow portion 25 vconnected to aninlet pipe 26. The latter is itself connected to the base of casing l by piping not shown. In the plane of cylinders 4, shaft 2 is so cut as to leave two crescent-shaped recessesdl and 28 (Fig. 2) adapted to respectively form an inlet and an outlet collector, the former being connected to the hollow part 25 througha longitudinal bore 29, while the other communicates witha longitudinal bore 30 form,- ing a delivery channel towards the end of shaft 2 opposed to pipe 26 (Fig. 1). Shaft 2 is similarly arranged in the plane of cylinders 8 to form two recesses 3| and 32 (Fig. 3). The'former communicates with the above-described bore 29 which extends suillciently through the length of the The pump illustrated comprises. a general casso special delivery bore or channel 33 (l'f'igs. 1 and 3) extending towards the right end of shaft 2.

There is provided in the rear wall of casing I a vertical bore 34 adapted to form a high-pressure chamber. Bore 24 communicates with channel 32 through a non-return ball valve 35. And channel 30 in turn communicates with channel 83 through another non-return ball valve 36 (Figs. 1 and 4) Channels 30 and 88 open at the right hand end of shaft 2 (Fig. l) and they accommodate two pistons, 31 and 38 respectively, which bear against a common movable abutment 3| pressed towards the left by a strong spring 4. bearing against a cap 4| fixed to casing I and fitting over the end or shaft 2.

Shaft 2 is formed with a transverse port 42 (Fig. 1) providing a communication between channel 80 and the interior of casing I. Port 42 is normally closed by piston 31.

The rear wall of casing I also encloses a distributor comprising a horizontal transverse bore .42 (Figs. 1 and 4) which houses a double slidable piston-valve 44 with an actuating rod 45 passing through a stufiing box 46, the opposite end of the bore being closed by a cover 41. Bore 43 crosses the above-described vertical bore 34 and it is connected with two tubes 48 and 49 forming the delivery (or return) of liquid under pressure. These two tubes are connected with the two chambers of the cylinder of the hydraulic press or ram actuated by the pump. The two ends of bore 43 are connected with the inside of casing I through two small spring-loaded valves, each comprising (Fig. 5) a longitudinal bore ill enclosing a piston II pressed by a spring 52 against a shoulder forming a seat, spring 52 resting against a plug 53. A port 54, normally covered by piston 5!, provides a communication between bore 52 and the interior of casing I.

The operation is as follows:

Rotor 3 is driven through a pair of reducing gears 55 and 56, the former being, for instance, keyed on the shaft of an electric driving motor. Drum I2 being initially at its maximum eccentricity under the action of springs 20, the cylinders '3 and 5 deliver a large output of liquid under low pressure into the high-pressure chamber 34 through channels and 33. are at their left-hand position of Fig. 1 and port 52 is covered.

As the pressure rises, the reaction exerted by drum I2 against side member I4 causes the latter to rise against the action of springs 20 and the stroke of pistons 6 and I thus decreases, which tends to maintain the driving torque substantially constant in spite of pressure increase.

When the pressure reaches a suflicient value, pistons 31 and 38 are displaced towards the right Pistons 31 and 38 against the action of spring 40, whereby port 42 is progressively uncovered, which suppresses the action of cylinders 4, the delivery of which freely returns to casing I. Ball 36 prevents liquid from flowing back from channel 33, so that the pressure goes on rising under the sole action of the smallsection cylinders 5. The reaction against side members I4 being thus diminished, the eccentricity of drum I2 returns to a maximum or at least to a relatively high value.

- It will be remarked that the pressure rapidly reaches such a value that piston 38, acting alone, maintains spring 40 in the compressed state. Piston 31 is thus free and the by-pass through port 42 is efiected without any counterpressure. For instance if spring 4| is so set that port 42 begins to be uncovered at a presure p under the action or pistons 31 and 38, ball ll closes as soon as this pressure is attained and the delivery of": .7 cylinders 4 through port 42 takes place under a" counter-pressure :2. But the pressure acting on piston 38 rises and this counterpressure decree-1C, the sum of the forces applied by 'the two pistol! on abutment 39 remaining substantially constant When the delivery pressure of cylinders 8 reaches a valve P, cylinders 4 thus operate without any counterpressure.

As the pressure continues to rise, side members I4 again rise under the reaction of pistons 1 against drum l2, But, owing to the small crosssection of cylinders 5, this reaction is reduced and it would be insufllcient to maintain the driving torque substantially constant. It is therefore-alsisted by the hydraulic device 2I-22 which is connected to the high-pressure chamber 34 through an external piping diagrammatically in dicated at 51 in Fig. 1.

The liquid under high pressure within chamber 34 flows towards the hydraulic press or the like through one of pipes 48, 49 (Fig. 4) according to the position of the double piston valve 44 (in Fig. 4, the outlet takes place through pipe 48), while the other pipe (pipe 49 in Fig. 4) is connected with casing I through the corresponding springloaded valve 5I-52 which ensures a sufllcient counterpressure to prevent air admission into the liquid circuit.

I claim:

1. In a hydraulic pump, a casing, a shaft having its opposite ends fixedly supported in said casing, a rotor rotatably supported on the shaft, drive means for rotating said rotor, two series of cylinders in said rotor disposed radially of said shaft, the cylinders of one series being of a' different diameter than the cylinders of the other series and being spaced therefrom axially of the shaft, pistons operatively disposed in said cylinders, a drum surrounding said rotor; connecting means movably securing the outer ends of the pistons to said drum, yieldable means initially retaining the drum in eccentric relation to the axes of the shaft and rotor, fluid distributing means in said shaft including inlet and outlet ports to said cylinders, a fluid supply connection at one end of said shaft in communication with said inlet ports, and a fluid high pressure chamber in said casing having one-way valve controlled communication with said outlet ports, whereby upon rotation of said rotor, said pistons are reciprocated and act to pump fluid through said fluid supply connection into said pressure chame her; said fluid distributing means including a pair of elongated bores communicat ng at corresponding ends thereof with the outlet-parts of the respective series of cylinders, said bores having said one-way valve controlled communication with said high pressure chamber, a by-pass fluid port in one of .said bores, a spring backed piston in said one bore normally closing said by-pass port, whereby upon increased pressure within said one bore, the piston is moved against the action of said spring to open the by-pass port and thus render the associated series of cylinders inoperative to pump fluid into said high pressure chamber.

2. In a hydraulic pump, a. casing, a shaft having its opposite ends fixedly supported in said casing, a rotor rotatably supported on the shaft, drive means for rotating said rotor, two series of cylinders in said rotor disposed radially of said shaft, the cylinders of One series being of a diiferent diameter than the cylinders of the 5 other series and being spaced therefrom axially of the shaft, pistons operatively disposed in said cylinders, a drum surrounding said rotor, connecting means movably securing the outer ends of the pistons to said drum, yieldable means initially retaining the drum in eccentric relation to the axes of the shaft and rotor, fluid distributing means in said shaft including inlet and outlet ports to said cylinders, a fluid supply connection at one end of said shaft in communication with said imet ports, and a fluid high pressure chamber in said casing having one-way valve controlled communication with said outlet ports, whereby upon rotation of said rotor, said pistons are reciprocated and act to pump fluid through said fluid supply connection into said pressure chamber; said drum being rotatably supported within a pressure member supported within the casing by guide means for vertical movement thereof in accordance with changes in the eccentricity of the drum as occasioned by reaction of the pistons against fluid under pressure.

3. In a hydraulic pump, a casing, a shaft having its opposite ends fixedly supported in said casing, a rotor rotatably supported on the shaft, drive means for rotating said rotor, two series of cylinders in said rotor disposed radially of said shaft, the cylinders of one series being of a different diameter than the cylinders of the other series and being spaced therefrom axially of the shaft, pistons operativeiy disposed in said cylinders, a drum surrounding said rotor, connecting means movably securing the outer ends of the pistons to said drum, yieldable meansv initially retaining the drum in eccentric relation to the axes of the shaft'and rotor, fluid distributing means in said shaft including inlet and outlet ports to said cylinders, a fluid supply connection at one endof said shaft in communication with said inlet ports, and a fluid high pressure chamber in said casing having one-way valve controlled communication with said outlet ports, whereby upon rotation of said rotor, said pistons are reciprocated 'and act to pump fluid through said fluid supply connection into said pressure chamher; a bore in said casing intersecting and communicating with said high pressure chamber, fluid outlets from said bore to the exterior of the casing, fluid outlets from said bore to the interior to rounding the rotor and rotatably supported within the side members, two series of cylinders in the rotor in radial relation to the shaft, the cylinders of one series being of substantially greater diameter than the cylinders of the other series and spaced therefrom axially of the shaft, spring means reacting against said side members for initially retaining the drum in eccentric relation to the axes of the shaft and rotor, pistons operatively disposed in the cylinders and having their outer ends 'pivotaily and circumferentially slidably connected withthe drum, fluid distributing means in the shaft including inlet and outlet ports to the cylinders, a fluid supply connection from the casing to said inlet ports, a vertically disposed fluid pressure chamber in said casing, said outlet ports of the cylinders of the respective series thereof communicating with an elongated bore included in said distributing means, and one-way valve controlled ports between said bores and said pressure chamber adjacent the other end of the shaft.

5. The structure according to claim 4, together with a spring backed piston in each of said bores beyond said one-way valves, a port providing communication between one of said bores and said casing, the associated piston normally closing said port and being movable under increase of fluid pressure by said pump to open said port.

6. The structure according to claim 4, wherein said side members are interconnected by a cross member above the casing, a piston operatively disposed in a cylinder in the casing and having its upper end engaged with said cross member, and a fluid connection between said pressure chamber and said cylinder.

7. The structure according to claim 4, wherein said side members are interconnected by iongitudinal stays, vertical columns extending upwardly from said stays through openings in said casing for providing said vertical sliding movement, a cross-member interconnecting the upper ends of the columns, a pair of rods extending upwardly from said casing and through openings in said cross-member, and said spring means surrounding said rods and engaging said crossmember.

8. The structure according to claim 4, together with a horizontal bore in said casing intersecting and communicating with said pressure chamber fluid outlets from said bore at each side of said pressure chamber leading to said casing and exterior thereof, and a double piston valve slidably disposed in said bore for controlling said outlets.

9. In a hydraulic pump, a plurality of sets of rotary pump cylinders and pistons, the cylinders of each set having a different diameter with respect to those of the other sets respectively, fluid distributing means for each set comprising inlet and outlet ports, a common high-pressure chamber; one-way valve means connecting the outlet port of each set to said high-pressure chamber; means for by-passing the inlet and outlet ports of each set of cylinders of larger diameter; and pressure-responsive means for actuating said bypassing means to render said sets inactive in succession commencing with those of largest diameter.

ELYSEE EYNARD.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Hautzenroeder Oct. 9, 1945 

